| The synthesis, characterization, and thermal behavior of ADMET-made models of ethylene/isobutylene (EIB), ethylene/methyl methacrylate (EMMA) and ethylene; methacrylic acid (EMAA) copolymers with sequence ordered pendant groups are described in Chapter 3. These model copolymers are compared to their random copolymer counterparts, which are made using chain-growth polymerization methods. They exhibit sharper melting transitions relative to the random copolymers, but their melting points occur at lower temperatures. Also, these new model copolymers are compared with a previously studied series of ADMET ethylene-based model copolymers, and support the previous finding that the melting points of the model periodic copolymers decrease with increasing steric bulk of their pendant groups. Only one of the model copolymers failed to crystallize, and this property was used advantageously to produce the amorphous telechelic hydrocarbon diols that are discussed in Chapter 4.; In Chapter 4, several methods are described for the production of perfectly bifunctional, completely amorphous telechelic hydrocarbon diols using ADMET chemistry. The hydrocarbon backbone is based on the symmetrical gem-dimethyl substituted α,ω-diene monomer that was used to make one of the EIB model copolymers. Three monofunctional reactants (MR's), each with a different methylene sequence length, were used to end-cap the polymer chains. All three MR's could be used to make: difunctional telechelic diols, but the use of the shortest MR led to relatively poor molecular weight control and the use of the longest MR led to a semicrystalline material. The best results were obtained when the medium length MR was used in combination with the polymerization-depolymerization production method. The resulting telechelic diol was perfectly bifunctional within NMR and IR spectroscopy detection limits, and it was completely amorphous with a glass transition temperature at −56°C.; Additionally, a simple two-step procedure was developed that was more efficient than the polymerization-depolymerization method. It involved the direct ADMET polymerization of the α,ω-diene monomer in the presence of a MR with a benzyl ether protecting group, followed by a one-pot hydrogenation-deprotection step. However, this method was only tested with the longest MR, which yielded the semicrystalline material. An improvement was suggested, involving the use of a shorter benzyl ether MR, that might lead to a perfectly difunctional, completely amorphous telechelic hydrocarbon diol using this simpler procedure. |
